The blown film extrusion process is a vertically oriented extrusion process that requires a structure, commonly called a “blown film tower” to host equipment at different elevations and provide physical space to enhance film cooling. The blown film process is a well known type of thermoplastic extrusion process where raw materials such as pellets of solid polyethylene are placed into and gravity fed through a hopper. A feed screw and electric type heater component inside a barrel beneath the hopper further mushes and melts the pellets. A resulting uniform homogenous melted material (having the consistency of a jello type material) is then fed through a coloring dye into the bottom of a blown film tower, where a compressed air supply injects air into a holder forming a film bubble. The resulting bubble rises upward through the middle of the tower to a shaping device such as a hollow funnel adjacent to the top of the tower having a narrow upper opening where a conventional nip and roll assembly on top of the tower allows for resulting film to be pulled out.
Conventional blown film towers are usually custom made for each worksite to specific heights and dimensions. These towers include many raw steel type materials and extensive labor installation time for assembly. Generally, the components of these conventional towers are permanently welded in place. Installing these towers can take up to 45 days or more to assemble and cost up to and over some $400,000 to complete. U.S. Pat. No. 3,980,418 to Schott, Jr.; U.S. Pat. No. 4,243,363 to Mulcahy; U.S. Pat. No. 4,355,966 to Sweeney et al. and U.S. Pat. No. 4,402,656 to Schott, Jr., each show blown film processing systems that use conventional type towers having the types of problems previously described.
Other Patents exist on scaffolding type systems and stair case units that also fail to overcome problems described above. These patents include U.S. Pat. No. 3,752,262 to Helms; U.S. Pat. No. 3,768,016 to Townsend et al.; U.S. Pat. No. 3,807,120 to Viandon; U.S. Pat. No. 3,817,347 to Spencer; U.S. Pat. No. 4,867,274 to Langer; U.S. Pat. No. 5,135,077 to Shalders and U.S. Pat. No. 5,491,939 to Wang.